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          <span class="refentrytitle">specfilt</span>
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        <p>specfilt — 
      Filters each channel of an input spectrum.
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        <h2>Description</h2>
        <p>
      Filters each channel of an input spectrum.
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        <h2>Syntax</h2>
        <pre class="synopsis">wsig <span class="command"><strong>specfilt</strong></span> wsigin, ifhtim</pre>
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        <h2>Initialization</h2>
        <p>
      <span class="emphasis"><em>ifhtim</em></span> --  half-time constant.
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        <h2>Performance</h2>
        <p>
      <span class="emphasis"><em>wsigin</em></span> --  the input spectrum.
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        <p>
      Filters each channel of an input spectrum. At each new frame of <span class="emphasis"><em>wsigin</em></span>, each magnitude value is injected into a 1st-order lowpass recursive filter, whose half-time constant has been initially set by sampling the ftable <span class="emphasis"><em>ifhtim</em></span> across the (logarithmic) frequency space of the input spectrum. This unit effectively applies a <span class="emphasis"><em>persistence</em></span> factor to the data occurring in each spectral channel, and is useful for simulating the <span class="emphasis"><em>energy integration</em></span> that occurs during auditory perception. It may also be used as a time-attenuated running <span class="emphasis"><em>histogram</em></span> of the spectral distribution.
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        <h2>Examples</h2>
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  wsig2    <span class="opc">specdiff</span>    wsig1         <span class="comment">; sense onsets</span>
  wsig3    <span class="opc">specfilt</span>    wsig2, 2      <span class="comment">; absorb slowly</span>
           <span class="opc">specdisp</span>    wsig2, 0.1    <span class="comment">; &amp; display both spectra</span>
           <span class="opc">specdisp</span>    wsig3, 0.1</pre>
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        <h2>See Also</h2>
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      <a class="link" href="specaddm.html" title="specaddm"><em class="citetitle">specaddm</em></a>,
      <a class="link" href="specdiff.html" title="specdiff"><em class="citetitle">specdiff</em></a>,
      <a class="link" href="spechist.html" title="spechist"><em class="citetitle">spechist</em></a>,
      <a class="link" href="specscal.html" title="specscal"><em class="citetitle">specscal</em></a>
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